This invention relates generally to bags employed in impact absorbing activities and more particularly to a collapsible bag which is useful in a variety of physical conditioning activities and which may be assembled by the user so he may selectively control both its hardness and its impact absorption characteristic.
Impact absorbing bags in various forms are well known in the prior art, particularly for purposes of physical conditioning. Such bags are useful as an aid in teaching punching and kicking techniques to students of karate. Boxers and military personnel have a long history of using impact absorbing bags as part of their conditioning process. Football coaches may employ impact absorbing bags as tackling dummies.
One physical conditioning bag currently known comprises an elongate flexible casing which is lined with foam sheet material along its interior lateral and bottom surfaces. The bag is then filled with a lightweight scrap material to provide bulk for the bag. Small packages of sand or other weighting material are disposed generally centrally of the bag's length within the scrap material and away from the walls of the bag to give the bag the desired impact absorption characteristic.
This prior art conditioning bag is characterized by several disadvantages. First, its structure makes it a relatively expensive bag to manufacture. This bag employs a relatively thick (2 - 3 inches) foam lining cushion material which is expensive initially from the standpoint of material cost. Additionally, this bag has a relatively complicated structure which makes it more desirable for a manufacturer, rather than a user, to assemble the bag. This same complicated structure makes the bag expensive to assemble because of the amount of manual labor required. The relatively thick foam lining must initially be fitted into the flexible casing. Thereafter, in a time consuming process, scrap material must be stuffed into the bag by hand with small packages of weighting material being disposed within the body of scrap material. A manufacturer assembling this bag has the further expense of maintaining an inventory of bulky, space consuming foam sheet material and scrap stuffing material, as well as heavy sand. All these costs must be passed on to the purchaser of the bag.
This known bag is also disadvantageous because once assembled, its hardness to contact and its impact absorption character are not adjustable by the user. Generally individual ones of such bags are purchased for use by a number of users in a karate dojo or gymnasium. The users may range over an entire spectrum, from inexperienced, relatively weak children to experienced, physically strong adults. It is clear that some individuals, by the nature of their lesser ability and strength would benefit more by practicing their punching and kicking techniques on a lighter weight, softer bag which would respond more to their blows than a heavier harder bag. Additionally the use of a too heavy, too hard bag by an insufficiently strong or skilled student can lead to injury. Such a student might find the reacting shock imparted to him upon his striking a too heavy bag too great for his striking arm or foot to absorb comfortably. On the other hand a more skilled student might not be sufficiently challenged by a too light bag. Too light a bag would respond by dancing wildly under his blows, be hard to strike rapidly because of that response, and not cause the more skilled student to exert himself. Most facilities serving a number of people of varying skills and strengths would not be in a position to buy a number of bags of varying hardness and impact absorption characteristics to suit all their users.
A third disadvantage is that once the bag is assembled by the manufacturer it must be shipped to the consumer who must bear the transportation cost, not only for the casing, but also for bulky and heavy stuffing materials.
A fourth disadvantage is that this prior art bag is subject to breakdown from the punishment it endures, which breakdown results in a change in both the punching surface and the impact absorption characteristics of the bag. The breakdown arises when the packages of sand rupture and the sand works its way through the scrap material to the bottom of the bag. As a result of this breakdown, the bottom surface of the bag becomes very hard due to the sand accumulation there. The upper lateral surface portions of the bag become much softer because the breakage of the sand packages has permitted adjacent scrap material to migrate and fill the voids left by the breakdown of the sand packages. Consequently, less scrap material is available to keep the lateral surfaces of the bag firm. Thus, the punching surface of the bag changes. Additionally, with the punching surface softened and the sand accumulated at the bottom of the bag, the impacts delivered to the bag by a user are not absorbed in the way they would be if the surface was hard. The soft surface gives under the impacts and does not transmit them directly to the accumulated sand. As a result, this prior art bag upon breakdown, tends to dance wildly upon impact.
A fifth disadvantage is that once such a bag is assembled it is not particularly portable. Considering the fact that athletes, particularly serious students of karate, will attend competitive meets and will be desirous of working out prior to the competition, it would be desirable if their workout bags could be easily transported to such a meet. The prior art bag, once assembled, is a bulky, heavy object which is not amenable to transport. No advantage would be obtained by disassembling the bag, transporting its casing alone to the meet, and reassembling the bag at the meet with components available there. The bag's components i.e., relatively non-breakable sand packages, scrap material, and relatively thick foam liner, would not be readily or cheaply available at the meet. Even if they were available it would be a major task to tear down and reassemble the bag.
A sixth disadvantage is that once such a bag is assembled, it will commonly have a rather bumpy appearance which is not particularly pleasing to the eye.
Other types of impact absorbing bags are known in the prior art. These do not overcome all the above noted disadvantages. A bag useful for conditioning boxers is shown in U.S. Pat. No. 2,156,831. The bag comprises an elongate flexible leather casing which is filled with sand or other material. The bag is dimensioned so that when filled it presents an approximately life size target for the boxer. The mass of sand required to fill the bag gives the bag its impact absorption quality. The use of such sand filler, contiguous with the interior of the bag, makes the surface of the bag hard to the touch. Gloves are generally used with such a bag and once assembled, the physical characteristics of the bag are not adjustable.
Another bag, shown in U.S. Pat. No. 2,344,360, comprises an elongate flexible casing filled with scrap material such as cotton fibers. This conditioning bag is necessarily lighter in weight than the sand filled bag and could be used without gloves. However, once formed, its physical characteristics are also fixed.
It is therefore an object of this invention to provide such a bag which overcomes the aforementioned disadvantages and more particularly to provide such a bag for impact absorbing activities which is simply constructed so that it may be transported in a collapsed compact condition and then be readily assembled by the user.
It is a further object of this invention to provide such a bag which is expanded to a usable condition by the use of fungible, readily available bulk forming and weighting materials supplied by the user thereby obviating the need to ship the same with the collapsed bag.
It is another object of this invention to provide such a bag which, upon assembly, is easily adjustable both with respect to its hardness and its impact absorption characteristics.
These and other objects are obtained by a preferred construction including a flexible casing and a collapsible envelope disposed within the casing. The interior of the envelope is adapted to receive and contain material for expanding the envelope within the casing. When the envelope is expanded within the casing, the exterior surface of the envelope defines an open, erect cavity which is accessible from outside the casing. The erect cavity is adapted to receive material for imparting a selected weight to the bag.
An important feature of the described embodiment resides in the utilization of an envelope which comprises a generally elongate annular shape. The core of the elongate angular envelope is opened to permit access from the casing exterior so that any desired weight of filler material, within the capacity of the bag cavity, may be disposed in the cavity by the bag's user to impart a desired impact absorption characteristic to the bag.
Another important feature is the employment of a hermetic envelope which includes a compressed air valve. The user of the bag is thus able to himself inflate or deflate the envelopes with compressed air to produce a desired hardness in the bag.
Still other features, advantages and full understanding of the invention will be had from the following detailed description when taken in conjunction with accompanying drawings.